The proposed research is directed toward examining the biosynthesis and fate of specific membrane glycoproteins and glycolipids in the cell body, axon, and terminals of a single identified neuron. The neuron is designated R2 and is found in the abdominal ganglion of the marine mollusc Aplysia californica. Glycoproteins and glycolipids of R2 can be labeled by injecting 3H-L-fucose or 3H-N-acetylgalactosamine directly into the cell body. Only 5 major 3H-glycoproteins are synthesized under these conditions, one of which is associated with the external membrane of the cell body and another with the vesicle fraction. The distribution of these two labeled components throughout the neuron will be determined by biochemical and morphological means and the effects of electrical activity on the distribution will be assessed. In addition the polypeptide and oligosaccharide moieties of the two glycoproteins will be analyzed. We will also inject R2's axon in order to compare its synthetic capabilities with those of the cell body. The metacerebral cell, another identified neuron, has three sets of synapses which are functionally and anatomically distinct. The identity and disposition of individual glycoproteins of these three classes of synapse will be examined after intrasomatic injection of sugar precursors.